Well, there are a few things you can do.
Unfortunately with extract brewing you are a bit limited as you are at the mercy of the extract producer.
There are a few things that contribute to head and head retention and they all are dependent on how the grain is mashed. So as an extract brewer you have no control over that part.
If you are thinking of the creamy dense heads on a Guinness or other stout poured on draft those are do to the method of serving, in addition to the dextrinous body of the beer. They use a special faucet with a constrictor plate/ high pressure and a special "beer gas" which is a combo of CO2 and Nitrogen.
I would attempt to explain the head producing elements of a brew if I were more sober, but alas, at the moment I am not and I would fail hard. I will leave it to a much more sober and intelligent fellow forum friend...
Here is a cheap trick you can try. A poor man's cheating method for that creamy head. Get yourself one of those "flavor injectors" used to inject marinade into meat. They look like a giant syringe. Pour your stout leaving some room in the glass, draw an ounce up into the syringe and then squirt it back in. You will get the cascading effect of a nitro poured beer and the dense foamy head. It knocks the CO2 out a bit but it has a neat effect.